CN111868535A

CN111868535A - Method and circuit for detecting water immersion and electronic equipment

Info

Publication number: CN111868535A
Application number: CN201880091242.2A
Authority: CN
Inventors: 张昊; 夏豪; 鹿楠; 张俊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-10-10
Filing date: 2018-10-10
Publication date: 2020-10-30
Anticipated expiration: 2038-10-10
Also published as: EP3855193B1; US20210341351A1; EP3855193A1; EP3855193A4; WO2020073253A1; US11566964B2; CN111868535B

Abstract

A method, a circuit and electronic equipment for detecting the immersion of an electrical interface relate to the technical field of communication and are beneficial to improving the accuracy of detecting the immersion of the electrical interface. The circuit includes: the first electrical interface comprises a grounding pin and is used for grounding when the first electrical interface works; and a first pin; one end of the resistor module is electrically connected with the first pin; the alternating current signal source is electrically connected with the other end of the resistance module and is used for generating an alternating current detection signal; the voltage detection module is connected with the first pin and used for detecting the maximum voltage value and the minimum voltage value on the first pin in the period of the alternating current detection signal; and the controller is respectively connected with the alternating current signal source and the voltage detection module and is used for controlling the alternating current signal source to generate an alternating current detection signal and determining that the first electrical interface is immersed when the difference value between the maximum voltage value and the minimum voltage value is smaller than a first threshold value.

Description

Method and circuit for detecting water immersion and electronic equipment

Technical Field

The present application relates to the field of circuit technologies, and in particular, to a method and a circuit for detecting water immersion, and an electronic device.

Background

Currently, electronic devices can achieve a waterproof function through a sealed structure. But there are also some leaky or conditionally leaky electrical interfaces or devices in electronic equipment, such as: universal Serial Bus (USB) interface, Pogo pin, earphone jack, SIM card interface, and mic, speker voice channel.

For such leaky electrical interfaces or devices, water is likely to be flooded. For example: splashing during hand washing, perspiration on the user's hand, and the like. Therefore, it is necessary to detect the water immersion of such an electrical interface or device that leaks, and to take appropriate protective measures after the water immersion is detected.

In the prior art, detection can be performed by a photoelectric water immersion sensor or a float type liquid level detection method. However, both of these detection methods require the electrical interface or device being detected to be completely immersed in water in order for immersion to be detected. However, in most cases, the electrical interface is not completely immersed in water, but rather is splashed into small amounts of water, or into small amounts of sweat, etc. These two detection methods are not detectable in the case of these common immersion in small amounts of water.

Disclosure of Invention

The application provides a method, circuit and electronic equipment that detect soaks can detect out the condition of whether electrical interface soaks a small amount of water, and also can detect out when electrical interface is in charged state, is favorable to promoting the degree of accuracy that detects electrical interface soaks.

In a first aspect, the present application provides a method for detecting flooding, which is applicable to an electronic device including a first electrical interface, a resistor module and an ac signal source, wherein one end of the resistor module is electrically connected to a first pin of the first electrical interface, the other end of the resistor module is electrically connected to the ac signal source, and a ground pin of the first electrical interface is grounded when the first electrical interface operates, and the method includes:

an alternating current signal source of the electronic equipment outputs an alternating current detection signal; the electronic equipment detects the maximum voltage value and the minimum voltage value on the first pin in the period of the alternating current detection signal; if the difference between the maximum voltage value and the minimum voltage value is less than the first threshold, the electronic device determines that the first electrical interface is flooded.

Therefore, whether the electronic equipment is soaked in water can be accurately detected when the electrical interface of the electronic equipment is in a charging state or a non-charging state. Furthermore, when the electrical interface of the electronic device is immersed in a small amount of water, it can be detected that the electrical interface of the electronic device is immersed in water. Therefore, the detection method provided by the embodiment of the application can improve the accuracy of detecting the immersion of the electronic equipment. In addition, the resistor module, the alternating current signal source and devices used in the voltage detection circuit adopted in the method provided by the embodiment of the application are low in cost.

In one possible implementation, the total resistance value of the resistance module is greater than 100 kilo ohms; the frequency of the alternating current detection signal is between 10 and 50 hertz.

In one possible implementation, the outputting, by an ac signal source of an electronic device, an ac detection signal includes: when the first electrical interface is detected to be in a charging state, the electronic equipment controls the alternating current signal source to output an alternating current detection signal; or, in response to detecting that the user starts the operation of the detection function, the electronic device controls the alternating current signal source to output an alternating current detection signal; or when the electronic equipment is detected to be in the power-on state, the electronic equipment controls the alternating current signal source to output the alternating current detection signal.

In a second aspect, a circuit for detecting water immersion of an electrical interface is provided, comprising: a first electrical interface, the first electrical interface comprising: the grounding pin is used for grounding when the first electrical interface works; and a first pin; one end of the resistor module is electrically connected with the first pin; the alternating current signal source is electrically connected with the other end of the resistance module and is used for generating an alternating current detection signal; the voltage detection module is connected with the first pin and used for detecting the maximum voltage value and the minimum voltage value on the first pin in the period of the alternating current detection signal; and the controller is respectively connected with the alternating current signal source and the voltage detection module and is used for controlling the alternating current signal source to generate an alternating current detection signal and determining that the first electrical interface is immersed when the difference value between the maximum voltage value and the minimum voltage value is smaller than a first threshold value.

In a possible implementation manner, the first electrical interface further includes a power pin for receiving an operating power when the first electrical interface is in operation.

In one possible implementation, the first electrical interface is a Universal Serial Bus (USB) interface.

In one possible implementation, the first interface is an ID pin.

In one possible implementation, the voltage detection module is an analog-to-digital converter.

In one possible implementation, the controller is a processor.

A third aspect, an electronic device, comprising: the detection device comprises a processor, a memory, a first electrical interface, a resistance module and an alternating current signal source, wherein one end of the resistance module is electrically connected with a first pin of the first electrical interface, the other end of the resistance module is electrically connected with the alternating current signal source, a grounding pin of the first electrical interface is grounded when the first electrical interface works, the alternating current signal source is connected with the processor, the processor is coupled with the memory, the memory is used for storing computer program codes, and the computer program codes comprise computer instructions which are read from the memory by the processor so as to enable the terminal to execute the method for detecting the electrical interface from being immersed in water in any one of the first aspect and the possible implementation manner of the first aspect.

A fourth aspect, an electronic device, comprising: a circuit for detecting flooding of an electrical interface as in the second aspect and any one of the possible implementations of the second aspect.

Drawings

FIG. 1A is a first circuit diagram of a prior art USB interface detecting flooding;

FIG. 1B is a second circuit diagram of a prior art for detecting the USB interface flooding;

FIG. 1C is a third prior art circuit diagram for detecting USB interface flooding;

fig. 2A is a first circuit diagram of a USB interface flooding detection apparatus according to an embodiment of the present disclosure;

fig. 2B is a second circuit diagram for detecting that the USB interface is immersed in water according to an embodiment of the present disclosure;

fig. 2C is a third circuit diagram for detecting that the USB interface is immersed in water according to an embodiment of the present disclosure;

fig. 2D is a fourth circuit diagram for detecting that the USB interface is immersed in water according to the embodiment of the present disclosure;

fig. 2E is a fifth circuit diagram for detecting that the USB interface is immersed in water according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Detailed Description

Fig. 1A (1) shows a circuit 200 for detecting that a USB interface is immersed in water in the prior art. The circuit 200 may include a USB interface 201, a dc detection power source 202, a voltage detection circuit 203, which may be, for example, an Analog-to-Digital Converter (ADC), and a voltage divider circuit 204.

The USB interface 201 may be disposed on a motherboard of the electronic device, and may be a charging interface and/or a USB data transmission interface connector for the electronic device. The USB interface 201 may include power pins (VBUS), data pins (D-and D +), ID pins (for identifying the end points of different cables), and ground pins (GND), which may be integrated on the same chip, which may be fixed to the housing of the USB cradle. The power pin may be used to access a power supply, such as a 5V dc power supply, for operation of the USB interface. The data pin is used for receiving/sending signals transmitted through the USB data line. The ID pin may be used to enable data transfer between devices without a Host (Host). The ground pin corresponds to the negative pole of the power supply.

The USB interface 201 is connected to the voltage detection circuit 203 and the voltage divider circuit 204 through ID pins, respectively. The voltage dividing circuit 204 includes a resistor R1 and a resistor R2 connected in series, one end of the resistor R1, and one end of the resistor R2 are both connected to the ID pin. The other end of the resistor R1 in the voltage divider circuit 204 is connected to the dc detection current 202, and the other end of the resistor R2 is grounded. The voltage detection circuit 203 is configured to detect a voltage value of the ID pin to ground (may be simply referred to as a voltage value on the ID pin). Optionally, in the present circuit, the voltage detection circuit 203 may also be replaced with a current detection circuit for detecting a current value flowing through the ID pin.

In the prior art, whether the USB interface is immersed in water can be determined by determining whether the detected voltage value on the ID pin (or the current value flowing through the point of the ID pin) changes. If the voltage value on the ID pin (or the current value flowing through the ID pin) is detected to be changed, the USB interface can be considered to be soaked. Here, the description will be given taking the detection of the voltage value at the ID pin as an example.

When the USB interface is in an uncharged state (i.e. the VBUS pin is not connected to the operating power supply), and the USB is not immersed in water, it can be detected that the voltage value on the ID pin is a fixed value.

This is because: as shown in (2) of fig. 1A, an equivalent circuit diagram of the circuit 200 is shown. From this circuit diagram, it can be seen that: the voltage detection circuit 203 detects that the voltage value on the ID pin is the divided voltage value of the dc detection power supply 202 at R2. Since the voltage of the dc detection power supply 202 and the values of the voltage dividing resistors (R1 and R2) are constant, the voltage value at the ID pin is also a fixed value. Specifically, the voltage on the ID pin (point a) when not charged and not immersed: va0 is expressed by vbatt/(1 + R1/R2), where vbatt is the voltage value output by the dc detection power supply 202, and since vbatt, R1 and R2 are fixed values, Va0 is a fixed value. If the USB interface is still in the uncharged state but is immersed in water, it can be detected that the voltage value on the ID pin is not the fixed value, but changes.

This is because: as shown in (1) of fig. 1B, a circuit diagram 300 is formed after the USB interface is immersed in water when the USB interface is in the charging state. In this circuit diagram 300, the equivalent resistance R3 forms an equivalent resistance for water between the ID pin and the GND pin. As shown in (2) of fig. 1B, an equivalent circuit diagram of the circuit 300 is shown. As can be seen from the equivalent circuit diagram, the equivalent resistor R3 is connected in parallel with the resistor R2, and then connected in series with the resistor R1. At this time, the voltage value on the ID pin should be the divided voltage value after the R2 and the R3 are connected in parallel. Compared with the case of no water immersion, the detected voltage value on the ID pin changes because the resistance value of the parallel connection of R2 and R3 is different from the resistance value of R2 in the circuit 200.

Specifically, the voltage Va1 at the ID pin (point a) when the battery is not charged and immersed is vtest/(1 + R1/R2+ R1/R3). Compared with Va0, Va1 has the increased denominator of Va1, which is obviously smaller than Va0, so that the USB interface can be judged to be immersed by detecting the voltage change on the ID pin.

It should be noted that the method of the circuit 200 can be used only when the USB interface is in an uncharged state, and whether the USB interface is immersed in water. When the USB interface is in a charging state, the method detects whether the USB interface is immersed in water, and the condition of inaccuracy occurs. The reason is as follows:

as shown in (1) of fig. 1C, a circuit diagram 400 is formed after the USB interface is immersed in water when the USB interface is in the charging state. In the circuit diagram 400, the equivalent resistance R3 is formed by water between the ID pin and the GND pin, and the equivalent resistance R4 is formed by water between the VBUS pin and the ID pin. At this time, the VBUS pin is connected to a dc charging power supply (voltage value is VBUS) for USB charging.

Fig. 1C (2) shows an equivalent circuit diagram of the circuit 400. From this equivalent circuit diagram, it can be seen that: compared with the circuit shown in (2) of fig. 1A when the USB is not charged and submerged, the equivalent resistor R3 and the equivalent resistor R4 formed after the USB is submerged affect the voltage value on the ID pin. Separately, the influence of the equivalent resistor R4 and the dc charging power input at the VBUS pin is not considered. Since the total resistance value of the parallel connection of R3 and R2 becomes small, the divided voltage values also become small, that is, the detected voltage value on the ID pin becomes small. And II, if the influence of the equivalent resistance R3 is not considered. Since the dc charging power input from the VBUS pin will sink current into the voltage divider circuit through the equivalent resistor R4, the voltage value at the ID pin will become large. Taken together, the effect of the equivalent resistor R3 and the equivalent resistor R4 on the voltage level on the ID pin, one will cause the voltage level on the ID pin to become larger and the other will cause the voltage level on the ID pin to become smaller. Since the flooding in the USB interface has randomness, the amount of water is uncertain, the composition of the flooding is uncertain (conductivity is uncertain), and other factors cause uncertain resistance values of the equivalent resistor R3 and the equivalent resistor R4, the influence of the equivalent resistor R3 and the equivalent resistor R4 on the voltage value of the ID pin cannot be determined. In other words, when the USB interface is in the charging state, if the USB interface is immersed in water, the voltage value on the ID pin may be equal to the fixed value or within the normal fluctuation range of the fixed value under the common influence of the equivalent resistor R3, the equivalent resistor R4, and the dc power supply connected to the VBUS pin. That is to say, the detection method in the prior art can not detect that the USB interface is immersed in water.

Specifically, the voltage value of the ID pin (point a) during charging and flooding is:

va2 is detected as V/(1 + R1/R2+ R1/R3+ R1/R4) + Vbus/(1+ R4/R1+ R4/R2+ R4/R3) comparing Va2 and Va0, V detection/(1 + R1/R2+ R1/R3+ R1/R4) is compared with Va0, denominator is increased by R1/R3+ R1/R4, which is smaller than Va0, but Va2 is compared with Va0 and is increased by Vbus/(1+ R4/R1+ R4/R2+ R4/R3), so Va2 is compared with Va0, which may be equal or not greatly different (difference is within normal detection error range), and therefore, it may be too large to detect the interface of soaking in water for charging.

The technical scheme provided by the embodiment of the application can be used for detecting whether the leaked electrical interface or device in the electronic equipment is immersed in water. Whether the detected electrical interface or device is in a charging state or not or whether a pin with constant voltage exists in the detected electrical interface or device can be accurately detected whether the detected electrical interface or device is soaked or not. Electrical interfaces or devices that leak out of the electronic device include, but are not limited to: USB interface, Pogo pin, earphone socket, SIM card interface, and mic, speker sound channel, etc. The technical scheme provided by the embodiment of the application can also be used for carrying out water immersion detection on the specific position in the internal module or the surface of the electronic equipment. The embodiment of the application does not limit the detected object, the detected position and the like in the electronic equipment.

The following description will be given taking an example in which the technical scheme provided by the embodiment of the present application is applied to detecting whether the USB interface is immersed in water.

As shown in fig. 2A, a circuit 500 for detecting that a USB interface is immersed in water is provided in an embodiment of the present application. The circuit 500 includes a USB interface 501, a voltage detection circuit 502 (for example, an ADC), a processor 503, an ac signal source 504, and a resistor module (which may include one or more resistors and may be equivalent to a resistor Ra, and hereinafter, referred to as a resistor Ra).

The USB interface 501 and the voltage detection circuit 502 are similar to the USB 201 and the voltage detection circuit 203 in the circuit 200 shown in (1) in fig. 1A, and are not repeated.

It should be noted that, in the present application, the type of the USB interface 501 and the number of the power supply pin and the GND pin included in the USB interface 501 are not limited, and the USB interface 501 may include other pins besides the pins shown in fig. 2A.

The first pin of the USB interface 501 is connected to one end of the resistor Ra and the input end of the voltage detection circuit 502, and the first pin may be any spare pin in the USB interface 501, for example, an ID pin. The first pin is taken as an ID pin as an example for explanation.

The other end of the resistor Ra is connected to an ac signal source 504. The resistance value of the resistor Ra is usually set to be much larger than that of an equivalent resistor in which the USB interface is immersed in water. The resistance value of the equivalent resistor with the USB interface immersed in water can be determined by a large number of experiments by considering a plurality of factors including immersed components, immersed water quantity, immersed position and the like. The resistance value of the resistor Ra is determined according to the resistance value in the range. The method for the resistance value of the resistor Ra is not limited in the embodiment of the present application. For example: the equivalent resistance is typically in the order of 1K ohms (ohm), and the value of Ra may be set to a few hundred Kohm.

A voltage detection circuit 502, the input end of which is connected with the ID pin, for detecting the voltage value of the ID pin to the ground (may be simply referred to as the voltage value on the ID pin); the output is connected to the processor 503 for outputting the detected voltage value to the processor. In the embodiment of the present application, an ac power signal is used as the detection signal, and therefore, the voltage value on the ID pin also changes periodically. The voltage detection circuit 502 is configured to detect a maximum value and a minimum value of voltage values on the ID pin in one or more cycles, and to provide the detected voltage values to the processor 503 for processing.

The processor 503 may be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits configured to implement embodiments of the present Application, such as: one or more Digital Signal Processors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs). The processor 503 is connected to the ac signal source 504 and the voltage detection circuit 502, respectively.

The processor 503 may be configured to control the ac signal source 504 to Output an ac signal as a detection signal for detecting whether the USB interface 501 is immersed in water through, for example, a General Purpose Input/Output (GPIO) interface. The ac signal output by the ac signal source 504 may be, for example, a square wave, a sine wave, a triangular wave, or the like. The frequency of the ac signal needs to be determined according to the resistance Ra and the capacitance value of the equivalent capacitor in which the USB interface is immersed. The principle of determination can be referred to the following description of the principle of the detection method, and is not repeated here. The capacitance value of the equivalent capacitor of the USB interface immersed in water can be determined by a large number of experiments by considering a plurality of factors including immersed components, immersed water quantity, immersed position and the like. And determining the frequency range of the alternating current detection signal according to the capacitance value in the range. For example: the frequency value of the AC detection signal may be 10-50 HZ.

Optionally, the processor 503 may control the ac signal source 504 to output an ac signal when detecting that the electronic device is powered on. The processor 503 may also control the ac signal source 504 to output an ac signal when detecting that the USB interface is in the charging state. The processor 503 may further control the ac signal source 504 to output an ac signal after detecting that the user starts the operation of detecting the USB interface submergence function. The embodiment of the present application does not limit this.

The processor 503 may be further configured to calculate a peak-to-peak value of the voltage value detected by the voltage detection circuit 502 (i.e., a difference between a maximum value and a minimum value of the voltage value on the ID pin in one or more cycles) according to the voltage value collected by the voltage detection circuit 502, so as to determine whether the USB interface 201 is immersed in water. Specifically, if the peak-to-peak variation of the voltage value detected by the voltage detection circuit 502 is greater than the threshold, it is determined that the USB interface is immersed in water. Otherwise, the USB interface is not soaked in water. When calculating the peak-to-peak value of the detected voltage value, after calculating the difference between the maximum value and the minimum value of the detected voltage value in each period, calculating the average value of the obtained difference values to determine the peak-to-peak value. Or after the maximum value and the minimum value of each voltage value are respectively averaged, the average value of the maximum value and the average value of the minimum value are subtracted to obtain the peak-to-peak value. The embodiment of the present application does not limit the specific calculation method of the peak to peak value.

The processor 503 may also be configured to trigger a protection measure of the corresponding electronic device after determining that the USB interface 501 is immersed in water, for example, to prompt a user that the USB interface is immersed in water, or to adopt a power-off protection measure.

The principle of the detection method provided in the embodiments of the present application is described below, as follows:

the first scenario is: and when the USB interface is in a charging state, detecting whether the USB interface is soaked in water.

When the USB interface is in an uncharged state and is not immersed in water, the circuit 500 shown in fig. 2A is shown. The ac detection signal from the ac signal source 504 of the circuit 500 is connected to the ID pin through a resistor Ra. At this time, the detected voltage value on the ID pin may be about the voltage value of the ac detection power supply, and then the peak-to-peak value of the voltage value on the ID pin is also about the peak-to-peak value of the voltage value of the ac detection signal, which may be used as a reference for comparison, that is, a basis for setting a threshold.

When the USB interface is not immersed in water, air, plastic, or other substances are filled between the pins of the USB interface. After the USB is soaked in water, water is filled between the pins of the USB interface, and the dielectric constant of the water is higher than that of air, plastics and other substances and is in direct proportion to the capacitance value. Therefore, water between the pins of the USB interface forms an equivalent capacitance in addition to an equivalent resistance.

As shown in fig. 2B, a circuit 600 is provided for the embodiment of the present application when the USB interface is in a charging state and is immersed in water. In this circuit 600, the equivalent resistance Rb and the equivalent capacitance Cb are formed by water between the ID pin and the GND pin; the equivalent resistance Rc and the equivalent capacitance Cc are formed for water between the ID pin and the VBUS pin. And the VBUS pin inputs the dc power signal.

Because the water composition that soaks in the USB interface is different, and the water yield is different, and the electric conductivity is also different, so the equivalent resistance that forms is also different, and then also different to the influence of circuit 600, so need to divide the situation to see as follows:

in the first case, the conductivity of water immersed in the USB interface is strong.

Circuit 600 includes two power supply signals: a dc charging signal and an ac detection signal. When two power supply signals are separated, the capacitance of the dc charging signal (the voltage value is Vbus) has the physical property of passing ac and dc, so the equivalent resistances Cc and Cb do not affect the dc charging signal, which is equivalent to the dc charging power supply being directly grounded via the two equivalent resistances Rc and Rb connected in series. As shown in (1) in fig. 2C. Obviously, at this time, the dc voltage value at the ID pin is the voltage division value of the dc charging power supply at Rb (equal to Vbus × Rb/(Rb + Rc), noted as V1). Since the resistance values of the equivalent resistance Rc and the equivalent resistance Rb vary randomly depending on the amount of water entering the USB port, the composition of water, and the like, the value of V1 varies depending on the water immersion condition. However, V1 remains unchanged for the same submersion and therefore does not affect the peak-to-peak value of the voltage on the ID pin.

For the ac detection signal (the voltage value is denoted as Vac), the VBUS pin is equivalent to ground (this is because the VBUS pin provides a dc power signal, and the ac signal is zero or very small, and can be equivalently ground). Moreover, when the conductivity of the immersed water is strong, the resistance value of the equivalent resistor formed between the pins in the USB interface is very small, and is usually much smaller than the capacitive reactance value of the equivalent capacitor formed between the pins (i.e. much larger than the capacitance value of the equivalent capacitor). Therefore, the influence of the equivalent resistance on the circuit 600 is great, and the influence of the equivalent capacitance on the circuit 600 can be ignored. Then, the ac detection power source is connected in series with a parallel resistor (a resistor formed by connecting the equivalent resistor Rc and the equivalent resistor Rb in parallel) through the resistor Ra and then grounded, as shown in (2) of fig. 2C. When the conductivity of the water entering the USB interface is strong, the resistances of the equivalent resistor Rb and the equivalent resistor Rc are small and much smaller than the resistance Ra. At this time, the ac voltage value (denoted as V2, equal to Vac/(1+ Ra/Rb)) on the ID pin is extremely small, that is, the amplitude of V2 (the maximum absolute value of the ac power occurring instantaneously in one cycle) is extremely small, and therefore the peak-to-peak value of V2 is also extremely small.

For example, assume that the DC charging power supply of the USB interface is 5V, and the AC detection power supply is 1.8V to-1.8V. The resistance Ra has a value of 200Kohm, and the equivalent resistances Rb and Rc are both 1 Kohm.

When the USB interface is not soaked in water, the VBUS pin and the ID pin are disconnected, the direct-current charging power supply does not influence the voltage on the ID pin, and at the moment, the peak-to-peak value of the voltage on the ID pin is 1.8V- (-1.8V) ═ 3.6V.

After the USB interface is soaked in water, the VBUS pin is connected with the ID pin through equivalent resistors Rb and Rc formed by water.

When the ac detection power supply has a maximum voltage value of 1.8V, the total resistance of the parallel connection of the equivalent resistors Rb and Rc is 0.5Kohm, and then V2 equals to 1.8V × 0.5Kohm/(0.5Kohm +200Kohm) equals to about 0.0045V.

At this time, V1 is 5V × 1Kohm/(1Kohm +1Kohm) is 2.5V.

Therefore, the detected voltage on the ID pin is: Va-V1 + V2-2.5045V.

When the ac detection power supply has a minimum voltage value of-1.8V, the total resistance of the equivalent resistors Rb and Rc connected in parallel is 0.5Kohm, and then V2 equals-1.8V × 0.5Kohm/(0.5Kohm +200Kohm) equals to-0.0045V.

At this time, V1 is 5V × 1Kohm/(1Kohm +1Kohm) is 2.5V.

Therefore, the detected voltage on the ID pin is: va' ═ V1+ V2 ═ 2.4955V.

It can be seen that the peak-to-peak value of the detected voltage on the ID pin is Va-Va' 0.009V, which is much smaller than the peak-to-peak value (3.6V) when the USB interface is not flooded.

Taken together, the voltage value on the ID pin should be the sum of V1 and V2, where V1 is a stable voltage value and V2 floats up and down but has a very small amplitude. That is, the peak-to-peak value of the voltage value at the ID pin detected by the voltage detection circuit is also extremely small in comparison with the case where the USB interface is not immersed in water. Therefore, whether the USB interface is soaked in water can be judged by using the detected peak-to-peak value change of the voltage value on the ID pin.

In the second case, the conductivity of water immersed in the USB interface is poor.

When the conductivity of water immersed in the USB interface is poor, the equivalent resistance value between the USB pins can be considered to be infinite, and the capacitor has the physical characteristic of alternating current resistance and direct current, so that the direct current charging power supply is grounded by connecting two infinite equivalent resistances in series, and the VBUS pin, the ID pin and the GND pin are in an open circuit state. At this time, the dc charging power on the VBUS pin has no effect on the voltage on the ID pin.

For an ac detection signal (the voltage value is denoted as Vac), VBUS corresponds to ground. Then, the ac detection power source is equivalent to a parallel capacitor (a capacitor in which the equivalent capacitor Cc and the equivalent capacitor Cb are connected in parallel) connected in series through the resistor Ra and then grounded, as shown in fig. 2D. At this time, the resistor Ra and the parallel capacitor form a low pass filter (low pass filtering). The voltage on the ID pin (point a) is the output voltage of the low pass filter:

wherein f is the frequency of the alternating current detection power supply, and C is the capacitance formed by connecting the equivalent capacitor Cc and the equivalent capacitor Cb in parallel.

As can be seen from the above equation, the higher the frequency of the ac detection power supply, the greater the amplitude attenuation of the output voltage Va.

Furthermore, the low pass filter is a filtering method, and the rule is that low frequency signals can normally pass through, and high frequency signals exceeding a set critical value are blocked and weakened. The critical value may also be referred to as a cut-off frequency, and the cut-off frequency is calculated as follows:

at this cut-off frequency, the amplitude of the ac power source is attenuated by 3 dB. After the cut-off frequency, the amplitude of the ac power passing through the circuit decays rapidly as the frequency of the ac power increases.

Due to the attenuation of the amplitude, the voltage peak-to-peak value detected by the voltage detection circuit on the ID pin is also attenuated. That is, after flooding, the voltage peak-to-peak value on the ID pin will decay from twice the amplitude before flooding to a smaller voltage value. Therefore, whether the USB interface is soaked in water can be detected by detecting the change of the peak-to-peak value of the voltage on the ID pin.

When the USB interface is not immersed in water, substances such as air and plastic are filled between the pins of the USB interface, and these substances also form an equivalent capacitance, and the cut-off frequency of the low-pass filter is denoted as F1. After the USB is soaked in water, water is filled between the pins of the USB interface, and the dielectric constant of the water is higher than that of air, plastics and other substances and is in direct proportion to the capacitance value. The equivalent capacitance after immersion becomes large, and the cut-off frequency is inversely proportional to the capacitance value, that is, the cut-off frequency (denoted as F2) becomes small after immersion, that is, F1> F2.

If the frequency of the ac signal outputted from the ac signal source 504 is between F1 and F2, the amplitude of the ac signal passing through the low pass filter will not change substantially when the USB interface is not immersed in water. When the USB interface is immersed in water, the amplitude of the ac signal passing through the low-pass filter is greatly reduced, and then the peak-to-peak value is also greatly reduced. That is, whether the USB interface is flooded can be determined by controlling the frequency of the ac signal output by the ac signal source 504 to be between F1 and F2, and then by detecting the peak-to-peak value change after the voltage value on the ID pin.

The second scenario is: and when the USB interface is in an uncharged state, detecting whether the USB interface is soaked in water.

As shown in (1) of fig. 2E, the circuit 700 is after the USB is soaked when the USB interface is in the uncharged state. In this circuit 700, the equivalent resistance Rb and the equivalent capacitance Cc are formed by water between the ID pin and the GND pin.

If the conductivity of the water immersed in the USB interface is strong, the resistance of the equivalent resistor Rb is very small and is much smaller than the resistance Ra, the voltage value on the ID pin is very small, and the peak-to-peak value is very small.

If the conductivity of the water immersed in the USB interface is weak, the resistance of the equivalent resistor Rb can be regarded as infinite, and then the ac detection power source is equivalent to the circuit shown in (2) in fig. 2E, which is grounded through the resistors Ra and Cb. That is, the resistor Ra and the capacitor Cb form a low-pass filter. For the function of the low-pass filter, reference is made to the above description, and the description is not repeated here. Whether the USB interface is immersed in water can be determined by controlling the frequency of the ac signal output by the ac signal source 504 and then detecting the peak-to-peak value of the voltage value on the ID pin.

It should be further noted that the positional relationship among the power supply pin, the ground pin, and the pin for detecting the voltage peak value (i.e., the first pin) in the USB interface in the circuit diagram is merely an example. That is to say, the embodiment of the present application does not limit the positional relationship of the three pins in the USB interface, and as long as the circuit connection relationship formed by the immersed pins after the USB interface is immersed is the same as or similar to the circuit relationship in the present application, the embodiment of the present application can be applied to the detection method provided by the embodiment of the present application.

In summary, the present application provides a method for detecting that an electronic device is immersed in water, which can access a pin in an electrical interface of the electronic device to be detected by controlling an input ac signal with a frequency within a certain range and an internal resistance of the ac signal. And simultaneously, detecting the voltage value of the electric interface pin. And if the peak-to-peak value of the voltage value of the electric interface pin is smaller than a certain threshold value, the electronic equipment is considered to be soaked. In the embodiment of the application, when the electrical interface of the electronic equipment is in the charging state, whether the electronic equipment is soaked in water can be accurately detected. Furthermore, when the electrical interface of the electronic device is immersed in a small amount of water, it can be detected that the electrical interface of the electronic device is immersed in water. Therefore, the detection method provided by the embodiment of the application can improve the accuracy of detecting the immersion of the electronic equipment.

In addition, the resistors, the alternating current power supply, the ADC and other devices adopted in the method provided by the embodiment of the application are low in cost.

In some embodiments, in addition to determining whether the USB interface is immersed by determining whether the peak-to-peak value of the voltage value on the ID pin is smaller than the threshold value, that is, determining whether the USB interface is immersed by the ac detection signal through the change of the peak-to-peak value of the voltage after the low-pass filter composed of the internal resistance Ra and the equivalent capacitor formed by the water in the USB interface, the USB interface may be also determined whether the USB interface is immersed by the ac detection signal through another change after the low-pass filter. For example: when the alternating current detection signal is a square wave, the edge of the square wave can be gentle after passing through the low-pass filter circuit, and therefore whether the USB interface is soaked in water can be judged by detecting whether the slope of the edge of the square wave signal is gentle. The embodiment of the present application does not limit this.

In other embodiments, the peak-to-peak value may be obtained by other methods besides using the voltage detection circuit to obtain the voltage value on the ID pin and then obtaining the peak-to-peak value of the voltage value on the ID pin by the processor. For example: but may also be implemented by hardware circuits. For example: the input AC detection signal is input into the low-pass filter, then sent to a DC blocking circuit to block DC component, and then passed through a peak detection circuit to detect AC peak-to-peak value. The peak value detection circuit outputs the peak value to the comparator, the comparator compares the peak value with a preset threshold value, and then a detection result is output. The embodiment of the present application does not limit this.

Fig. 3 is a block diagram of an electronic device, and as shown in fig. 3, the electronic device may include a circuit for detecting whether the USB interface is immersed in water as shown in fig. 2A, and the electronic device has the same function as that for detecting whether the USB interface is immersed in water as shown in fig. 2A, and is not described again. The electronic device may further include a circuit for detecting whether other electrical interfaces or devices of the electronic device are immersed in water by using the same method as the circuit shown in fig. 2A, which is not limited in the embodiment of the present application.

For example, the electronic device in the present application may be a mobile phone, a tablet Computer, a Personal Computer (PC), a Personal Digital Assistant (PDA), a smart watch, a netbook, a wearable electronic device, an Augmented Reality (AR) device, a Virtual Reality (VR) device, an in-vehicle device, a smart car, a smart audio, a robot, and the like, and the specific form of the electronic device is not particularly limited in the present application.

It should be noted that the device structure shown in fig. 3 does not constitute a limitation of the terminal device, and may include more or less components than those shown, or combine some components, or arrange different components. Although not shown, the terminal device may further include a display, a battery, a camera, a bluetooth module, a Global Positioning System (GPS), and other modules, which are not described herein.

Through the above description of the embodiments, it is clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional modules is merely used as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device may be divided into different functional modules to complete all or part of the above described functions.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the modules or units is only one logical functional division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another device, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may be one physical unit or a plurality of physical units, that is, may be located in one place, or may be distributed in a plurality of different places. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The above description is only an embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions within the technical scope of the present disclosure should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

A method for detecting the flooding of an electrical interface, which is applicable to an electronic device including a first electrical interface, a resistor module and an AC signal source, wherein one end of the resistor module is electrically connected to a first pin of the first electrical interface, the other end of the resistor module is electrically connected to the AC signal source, a ground pin of the first electrical interface is grounded when the first electrical interface is in operation, and the method for detecting the flooding of the electrical interface comprises:

the alternating current signal source of the electronic equipment outputs an alternating current detection signal;

the electronic equipment detects a maximum voltage value and a minimum voltage value on the first pin in a period of the alternating current detection signal;

if the difference between the maximum voltage value and the minimum voltage value is smaller than a first threshold value, the electronic device determines that the first electrical interface is immersed in water.
The method of detecting submersion of an electrical interface of claim 1, wherein the total resistance value of the resistor modules is greater than 100 kilo-ohms; the frequency of the alternating current detection signal is between 10 and 50 Hz.
The method of detecting submersion of an electrical interface according to claim 1 or 2, wherein outputting an ac detection signal from an ac signal source of the electronic device comprises:

when the first electrical interface is detected to be in a charging state, the electronic equipment controls the alternating current signal source to output an alternating current detection signal;

or, in response to detecting that the user starts the operation of the detection function, the electronic device controls the alternating current signal source to output an alternating current detection signal;

or, when the electronic device is detected to be in the power-on state, the electronic device controls the alternating current signal source to output an alternating current detection signal.
A circuit for detecting submersion of an electrical interface, comprising:

a first electrical interface, the first electrical interface comprising:

the grounding pin is used for grounding when the first electrical interface works;

and a first pin;

one end of the resistor module is electrically connected with the first pin;

the alternating current signal source is electrically connected with the other end of the resistor module and is used for generating an alternating current detection signal;

the voltage detection module is connected with the first pin and used for detecting the maximum voltage value and the minimum voltage value on the first pin in the period of the alternating current detection signal;

and the controller is respectively connected with the alternating current signal source and the voltage detection module and is used for controlling the alternating current signal source to generate the alternating current detection signal and determining that the first electrical interface is immersed when the difference value between the maximum voltage value and the minimum voltage value is smaller than a first threshold value.
The circuit for detecting submersion of an electrical interface of claim 4, wherein the first electrical interface further comprises a power pin for receiving an operating power when the first electrical interface is in operation.
The circuit for detecting submersion of an electrical interface of claim 4 or 5, wherein the first electrical interface is a Universal Serial Bus (USB) interface.
The circuit for detecting submersion of an electrical interface of claim 6, wherein the first pin is an ID pin.
A circuit for detecting submersion of an electrical interface according to any one of claims 4 to 7, wherein the voltage detection module is an analog-to-digital converter.
The circuit for detecting submersion of an electrical interface of any one of claims 4-8, wherein the controller is a processor.
An electronic device, comprising: a processor, a memory, a first electrical interface, a resistive module and an ac signal source, one end of the resistive module being electrically connected to the first pin of the first electrical interface and the other end being electrically connected to the ac signal source, the ground pin of the first electrical interface being grounded when the first electrical interface is in operation, the ac signal source being connected to the processor, the processor being coupled to the memory, the memory being configured to store computer program code, the computer program code comprising computer instructions that, when read by the processor from the memory, cause the terminal to perform the method of detecting flooding of an electrical interface according to any one of claims 1-3.
An electronic device, characterized in that the electronic device comprises: a circuit for detecting submersion of an electrical interface according to any one of claims 4-9.